Earth tamper



Dec. 24, '1940.

EARTH TAMPER Filed Jan. 17, 1938 'z-sheets-sneet'l INVENTORV MATTHEW .3. F066 B:

2 ATTORNEY.

M 5. Ross EARTH TAHPER Dec. 24, 1940.

Filed Jan. 17, 1938 2 Sheets-Sheet 2 Patented Dec. 24, 1940 a I UNITED STATES PATENT OFFICE amass 4 (or. 9H0) This invention relates to improvements in earth tampers of the sheep foot type. r I

In making earth fills such as in road grading, dam construction and the like. it is essential that the earth be compacted and thoroughly tamped to prevent future settling. vTo effect thorough compacting of freshly filled earth. the sheep foot? type of tamper has been extensively used but heretofore they have been tractor-drawn.

When a tractor is used to draw the tamper the surface of the fill is unavoidably compacted by the tractor which tends to prevent the feet" or lugs of the tamper drums from penetrating into the earth. This produces an inferior result in that strata are left in the fill that are not thoroughly tamped. Further, when a tamper of this type is drawn by a tractor, the rolls or drums tend to skid or slide along over the earth instead of turning, which defeats thorough tamping. Again, tractor-drawn equipment is dimcult to turn around or to reverse.

It is an object of the present invention to .provide a self-propelled earth tamper, of the "sheep foot" type, that can be steered and reversed, and which is provided with individual drives to each drum or roll so that the above enumerated difllculties are substantially eliminated, and the ro-' tation of the drums is assured.

Other objects and advantages reside in details of design and construction, inclusive of a novel and eflicient renewable lug or foot for the tamper rolls and novel provision for steering the machine. These features will be more fully disclosed in the following description and in the drawings wherein like parts have been similarly designated and in which:

Figure 1 is a generalplan view of a tamper built according to the present invention:

Figure 2 is a side elevation of the same;

Figure 3 is a fragmentary end elevation as indicated by arrow ,3 in Figure 2, and illustrating certain details of construction:

Figure 4 is an: enlarged sectional detail view;

and

Figure 5 in Figure 4:

In the drawings reference character II denotes a general supporting frame thatis divided into two relatively movable sections it and ii, that are pivotally connected by a' king pin it, the inner ends of the section's overlapping for the reception ofthe pin.

a A broad turn-table bearing for the two sections is provided at I. and a mechanism comprising a hydraulic cylinder III on frame section bitrary designation.

5 is an elevation asindicated by arrow' instance, a hand a mechanical drive from the engine.

I, a pump 2| connected therewith by a valvecontrolled flexible conduit system 22, and a piston rod 23 attached to the end Ila of the frame section II, controls the alinement or an ular relation of the 'frame sections for steering purposes. 5 A- driving power unit, such as an internal com-' bustion engine 24, is mounted on the forward frame section l1 and delivers propelling power to each of four independent rolls or drums 25, through a transmission mechanism comprising a power take-oi! 20, transmission and reversing unit TL-adrive shaft 28, a longitudinal differential an, a propeller shaft 29 for the front rollsor drums; a cross differential 30, individual chain drives SI and I! for the front drums, a propeller shaft 38 for. the rear rolls or drums-universal joints I4 and SI and splined slip joint 88 in the rear propeller shaft, a second cross differential I1, and individual chain drives and 39 for the rear rolls. The terms "frontf' and "rear" are I used herein for convenience in description but the i machine operates equally well and 'at the same speed in either direction of travel so that there is,

in reality. no front or .rear except as an are Each roll ordrum 25 is iournalled for rotation in an individual sub-frame 40 that is spring-carried and pivoted to the main frame, transversely to the axis of the drums. Each roll or drum is provided with a plurality of radially project mg lugs or sheep feet" ll, an enlarged detail of one of which is shown in Figures 4 and 5.

Operation In use, the improved temper is self-propelled and may be steered by an operator by the'manipulation of three-way valves 42 and 4 3 to admit liquid delivered by the pump 2| to thecylinder 20, to move the'piston rod 23', which, in turn, moves the frame section II about the king pin II which will steer-the machine while travelling in either direction, the direction of travel being under controlv of the operator by reversible gear-, ing of a conventional 'type- Other-means for moving'the frame sections about the king pin for 45 purposes,- of steering, may be provided, as for wheel with suitable gearing or In the steering mechanism illustra e the pump II is driven constantly from the engine, and its output by-passes back in a closed; cycle I vwhen both control valves are closed.

Since the individuai rolls or drums are carried in individual pivotal frames, each drum is free to follow the contour-of the surface overwhich it travels independently of the others, and the individual chain drives for the drums assure their turning without skidding, so that the lugs or "feet" will do their tamping work efficiently. No other piece of equipment goes over the fresh fill and a thoroughly good Job of tamping is therefore eflected. 1

In Figures 4 and 5,'details are shown of a renewable foot that is well adapted for use with this improved tamper. A radial lug M is permanently fixed to the drum 25 and at its outer end the lug has an inwardly tapering hole or socket 35 to closely fit a similarly tapered shank 46 on a foot ii? that is preferably made of hard steel to resist wear. The shank is drawn firmly into the lug bydriving a wedge 48 through slots provided in the lug and the shank for the purpose. The small end of the wedge is split longitudinally, as at 49, so that each side thereof may be oppositely bent similarly to a cotter pin, to hold the wedge in place in the shank. The foot may be replaced when worn, by driving out the wedge to release it and inserting a new ioot in the lug. The root is preferably provided with square or a rectangular working surface and the shank and/or the lug may be either square or circular in cross section. Obviously, any suitable form of lug or foot can be used on the improved tamper.

What I claim and desire to secure by letters Patent is:

1. An earth tamper comprising a main frame composed of two overlapping sections joined by a king pin for limited relative pivotal movement, a motor carried on one section, two rollers having lugs iournalled on each section, in axial alignment with each other, and mechanism for transmitting driving power from the motor to each roller differentially and inversely according to the relative resistance to turning of each roller.

composed of two overlapping sections joined by a King pin for relative pivotal movement, a motor carried on one section, a pair of sub-frames pivotally mounted on each of the sections on axes substantially parallel to the normal directions of travel of the tamper, a roller journalled for rotation on each of the sub-frames on an axis transverse to the pivotal axes of said subframes, and mechanismfor transmitting driving power from the motor to each roller differentially and inversely according to the resistance to turning offered by the respective rollers.

4. An earth tamper comprising a main frame composed of two overlapping sections Joined by a king pin for limited relative pivotal movement, a motor carried on one section, a sub-frame pivotally mounted on each frame section on an axis substantially parallel to the normal direction of travel of the tamper, a roller journalled for rotation on each sub-frame on an axis transverse to that of the sub-frame, and mechanism for transmitting driving power from the motor differentially to each roller.

MATTHEW S. R088. 

